Scopelocheirus hopei (Costa in Hope, 1851)

Zettler, Michael L., Bastrop, Ralf & Lowry, James K., 2023, Ten thousand kilometres away and still the same species? The mystery of identity of Scopelocheirus sp. (Amphipoda: Scopelocheiridae) from the South Atlantic, Records of the Australian Museum (Rec. Aust. Mus.) 75 (4), pp. 609-622 : 616

Scopelocheirus hopei (Costa in Hope, 1851)

Figs 3–6

Callisoma hopei Costa, 1851: 5–6 , pl. 8, figs 1–2

Anonyx kroyeri Bruzelius, 1859: 45–46 , pl. 2, fig. 7

Callisoma kroyeri . —Sars, 1890: 54–55, pl. 19, fig. 2.— Lilljeborg, 1865a: 33–34

Scopelocheirus hopei . —Stebbing, 1906: 62.—Stephensen, 1923: 15–16.— Chevreux & Fage, 1925: 55–56, fig. 39–40.—Stephensen, 1928: 79, fig. 12(20).—Stephensen, 1929: 64, fig. 16(47).—Oldevig, 1933: 42, fig. 2 on p. 41.—Schellenberg, 1942: 111, fig. 88.—Stephensen, 1942: 76.— Lincoln, 1979: 50, fig.16.—Diviacco & Ruffo (in Ruffo, 1989): 544, fig. 372.— Kilgallen & Lowry, 2015: 9–12.—Zettler & Zettler, 2017: 80–83, figs. 47–49

Type locality. Mediterranean Sea , Gulf of Naples ( Italy)

Material examined. Stn. PP 46: Denmark, Kattegat, water depth 50 m; amphipod trap; 56.8492°N; 11.7498°E ; salinity at bottom 33 psu, temperature at bottom 10°C, oxygen 4.25 ml/l, collected 27 Aug 2018; several hundred individuals, males and females. Stn. PP 63: Denmark, Kattegat water depth 118 m; amphipod trap; 57.0451°N; 11.6441°E ; salinity at bottom 33.5 psu, temperature at bottom 9°C, oxygen 4.0 ml/l, collected 29 Aug 2018; several hundred individuals, males and females.

Remarks. Although the material from the Kattegat evaluated here falls exactly within the range of variation of Scopelocheirus hopei (see Zettler & Zettler, 2017), a differentiation from S. crenatus Spence Bate, 1857 (and less critically also from S. polymedus Bellan-Santini, 1985 ) cannot be made. Even considering the arguments of Sars (1890), Diviacco & Ruffo (1989), and Kilgallen & Lowry (2015), we find the distinguishing features of the two latter to be ambiguous. Scopelocheirus hopei and S. crenatus co-occur in the North Atlantic and North Sea, and S. hopei and S. polymedus in the Mediterranean Sea. However, the latter is restricted to the bathyal and the others are more common on the shelf. It is very likely that many of the deeper records of S. hopei , particularly those from the Mediterranean region, are in fact misidentifications of S. polymedus and should be re-examined to confirm their identity ( Kilgallen & Lowry, 2015). Two species have been genetically identified in the North Atlantic (see Fig. 11); S. hopei from the North Sea (Raupach et al., 2015) and an undetermined Scopelocheirus sp. occurring around Iceland ( Jażdżewska et al., 2018). Unfortunately, no material from the Mediterranean Sea, the type locality of S. hopei and S. polymedus , has been analysed to date. We have identified the specimen collected in the Kattegat as S. hopei based on our own experience and high probability (see Zettler & Zettler, 2017), but until further research this cannot be consolidated, as mentioned above. Therefore, we provide here full illustrations of the entity from the Kattegat, to facilitate any further research on this issue.

Figures

Figure 3. Habitus photograph of Scopelocheirus hopei (Costa in Hope, 1851), male, 6 mm, Kattegat (Denmark), stn. PP46.

Figure 4. Scopelocheirus hopei (Costa in Hope, 1851), male, 5.9 mm, Kattegat (Denmark), habitus, Stn. PP46.

Figure 5. Scopelocheirus hopei (Costa in Hope, 1851), male, 5.9 mm, Kattegat (Denmark), scale bar 200 µm, Stn. PP46.

Figure 6. Scopelocheirus hopei (Costa in Hope, 1851), male, 5.9 mm, Kattegat (Denmark), scale bar 200 µm, Stn. PP46.